Some patients may develop adverse reactions or side effects from substances called radiocontrast media. These substances are given to patients before an X-ray or computerized tomography (CT) scan. The substances improve the visibility of the internal organs, allowing healthcare providers to detect cancerous tumors and abnormal growths.

There are two main types of contrast media: barium sulfate and iodine. Barium sulfate is a white powder that is mixed with water. The agent is most often used to help healthcare providers see the internal organs of the digestive tract, such as the intestines. Barium sulfate is usually swallowed or administered as an enema. The substance will be excreted from the body in the feces.

Iodine-based radiocontrast media are can be used almost anywhere in the body. They are typically injected into veins, but they may also be injected into an artery, injected into the spine, or injected into the abdomen.

Iodine may be formulated as either an ionic compound or an organic (non-ionic) compound. Ionic compounds were developed first, and they are still widely used today. Although ionic compounds are more likely to cause side effects than organic compounds, adverse reactions are uncommon. Organic compounds have fewer side effects because, unlike ionic compounds, they do not separate into smaller particles once they dissolve in water. This means the concentration of particles dissolved in a fluid, also called osmolality, is one-half that of ionic agents. Substances with higher osmolality are more likely to cause adverse reactions.

Adverse reactions from radiocontrast media are rare and symptoms can range from mild to life threatening. Serious side effects include an anaphylaxis-like reaction and kidney damage. Normally, anaphylaxis reactions are allergic reactions that involve the immune system. When anaphylaxis reactions occur in response to radiocontrast media, the immune system is not involved. Therefore, it is not considered true anaphylaxis. Kidney damage may occur because the kidneys must break down the radiocontrast media.

Radiocontrast media should not be given to patients who have experienced adverse reactions in the past because they have an increased risk of experiencing reactions in the future.

Treatment for adverse reactions depends on the type and severity of symptoms. Commonly used treatments include electrical cardioversion, epinephrine, hemodialysis, isotonic fluid, and supplemental oxygen.

General: Although adverse reactions to radiocontrast media produce the same symptoms as allergic reactions, they do not involve the immune system. Also, prior sensitization is not required. This means the patient can develop an adverse reaction to radiocontrast media the very first time they receive the substance. Therefore, adverse reactions to radiocontrast media are not considered true allergic reactions.

Current research suggests that individuals who have asthma and/or allergies to food or medications have an increased risk of experiencing adverse reactions to radiocontrast media. The reason for this remains unknown.

Some reactions may occur with any dose of radiocontrast media, while others only occur if high doses of radiocontrast media are given to sensitive patients.

Dose independent: Anaphylaxis-like reactions may occur with any dose of radiocontrast media. For instance, severe adverse reactions can occur following injections as low as one milliliter of radiocontrast media.

True anaphylaxis reactions are allergic reactions because they involve the immune system. However, anaphylaxis-like reactions that occur in response to radiocontrast media do not involve the immune system. Therefore, it is not considered an allergic reaction. The exact cause of anaphylaxis reactions remains unclear.

Dose dependent: Most adverse reactions that are dependent on a specific dose of radiocontrast media are non-life threatening. They typically cause symptoms, such as hives, warmth, nausea, vomiting, or metallic taste in the mouth. However, kidney failure or damage has been reported with intravenous use of radiocontrast media. This may occur because the kidneys are responsible for breaking down the radiocontrast media.

Anaphylaxis-like reaction: Some patients may develop a severe reaction similar to anaphylaxis. Symptoms of an anaphylaxis-like reaction can vary from mild to severe and may be potentially life threatening. The most dangerous symptoms of an anaphylaxis-like reaction are low blood pressure, difficulty breathing, shock, and loss of consciousness, all of which can be fatal. Other symptoms may include chest pain or tightness, irregular heartbeat, hives, reddening of the skin, flushing, angioedema (swelling below the skin surface), nausea, abdominal cramping, vomiting, stuffy nose, red/itchy/watery eyes, and headache. Patients who develop symptoms of anaphylaxis should seek immediate medical treatment.

Tissue damage: Tissue damage can occur if the drug leaks into nearby tissues. The radiocontrast media has a toxic effect on the tissues it comes into direct contact with. This may result in compartment syndrome, which causes the nerves and blood vessels to become compressed. As a result, impaired blood flow may lead to muscle and nerve damage.

Other: Some patients may experience a sensation of warmth, metallic taste in the mouth, nausea, and vomiting.

Adverse reactions to radiocontrast media typically occur within 20 minutes after the substance is administered. Healthcare providers should monitor patients closely for at least 20 minutes for possible reactions to the substance, such as low blood pressure and difficulty breathing. If symptoms of an adverse reaction develop, the patient receives treatment immediately.

Patients who received radiocontrast media within the last seven days and experience symptoms, such as fatigue, upper respiratory tract congestion, weakness, diarrhea, chills, abdominal pain, pain near the injection site, rash, dizziness, headache, nausea, and vomiting, should be suspected of having a delayed reaction to the substance. Although delayed reactions to radiocontrast media do not usually require medical treatment, patients should call their healthcare providers if they experience any of these symptoms within seven days of receiving the substance.

Electrical cardioversion: Electrical cardioversion, or defibrillation, should be performed if the patient experiences irregular heart beats called arrhythmias. During the procedure, an electrical shock is delivered to the heart in order to make it beat in a regular rhythm. The patient's response to treatment dramatically decreases with time. In fact, the likelihood of success decreases by about 10% with each passing minute. Therefore, doctors who give patients contrast media should have fast access to defibrillators.

Epinephrine: A medication called epinephrine is used to treat a severe anaphylaxis-like reaction. Epinephrine is injected into the skin at a hospital. Epinephrine acts as a bronchodilator because it opens the patient's airway. It also constricts the blood vessels, which increases blood pressure. Patients who experience anaphylaxis may also be admitted to the hospital to have their blood pressure monitored and possibly to receive breathing support.

Hemodialysis: If kidney damage develops, the healthcare provider will monitor the patient's condition and make sure that he/she is hydrated. In rare cases, patients may require temporary or permanent hemodialysis. Dialysis is a method of removing toxic substances and waste from the blood because dysfunctional kidneys are unable to perform this function. During the procedure, a hollow tube, called a catheter, is inserted into a patient's vein at the hospital. The blood is then filtered through a dialysis machine to remove waste products from the blood. The filtered blood is then returned to the patient. This procedure typically lasts about three to four hours.

Supplemental oxygen: Patients who experience difficulty breathing may receive 10-12 liters of oxygen per minute with a facemask. If the patient's symptoms continue to worsen despite treatment, epinephrine should be injected immediately.

Patients who have low blood pressure may also receive high doses of oxygen.

Supportive care: Symptoms of delayed reactions generally resolve without any medical treatment. However, patients should visit their healthcare providers if they experience flu-like symptoms up to seven days after receiving radiocontrast media. Patients may receive supportive care with pain medications to treat headaches. Patients may receive antipyretics to treat fevers. Meperidine (Demerol®) may be used to treat tremors, and isotonic fluid may help treat low blood pressure.

There is no specific treatment for tissue damage that occurs when radiocontrast media leaks into body tissues. Instead, the affected area may be elevated and a cool compress may be applied to help relieve symptoms. If the pain continues to worsen after two to four hours, or if the skin begins to blister or circulation or sensation changes in the affected area, a plastic surgeon should be consulted. In such cases, surgery may be necessary to restore blood flow and prevent further muscle and/or nerve damage.

Note: Anaphylaxis-like reactions are considered medical emergencies that require immediate medical care. Therefore, integrative therapies should not be used in place of conventional medicine when an individual experiences an anaphylactic-like reaction.

Unclear or conflicting scientific evidence:

Acupuncture: Acupuncture is commonly used throughout the world. According to Chinese medicine theory, the human body contains a network of energy pathways through which vital energy, called "chi," circulates. These pathways contain specific "points" that function like gates, allowing chi to flow through the body. Needles are inserted into these points to regulate the flow of chi. Acupuncture plus point-injection has been found beneficial for hives. However, more research is needed to confirm these findings.

Needles must be sterile in order to avoid disease transmission. Avoid with valvular heart disease, infections, bleeding disorders or with drugs that increase the risk of bleeding (anticoagulants), medical conditions of unknown origin, or neurological disorders. Avoid on areas that have received radiation therapy and during pregnancy. Use cautiously with lung disease (like asthma or emphysema). Use cautiously in elderly or medically compromised patients, diabetics, or with a history of seizures. Avoid electroacupuncture with arrhythmia (irregular heartbeat) or in patients with pacemakers.

Traditional or theoretical uses, which lack sufficient evidence:

Burdock: Burdock is native to Europe and northern Asia. The root is used most often in herbal preparations. Traditionally, burdock has been used to treat hives. However, there is currently no human evidence on the safety and effectiveness for this use.

Avoid if allergic to burdock or other plants of the Asteraceae/Compositae family (ragweed, chrysanthemums, marigolds, daisies). Avoid with a history of dehydration, diabetes, heart disease, cancer, high blood pressure, or HIV. Stop use before surgeries/dental/diagnostic procedures. Avoid if pregnant or breastfeeding.

Chamomile: Chamomile is a common tea that has an apple-like smell and taste. Chamomile is a popular home remedy for many conditions, including skin and stomach discomfort. Although chamomile has traditionally been used to treat hives, scientific evidence is lacking. Currently, no human trials have evaluated the safety or effectiveness of chamomile for this use.

Avoid if allergic to chamomile or any related plants, such as aster, chrysanthemum, mugwort, ragweed or ragwort. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Use cautiously if driving or operating machinery. Avoid if pregnant or breastfeeding.

Detoxification therapy (cleansing): Detoxification is a broad concept that encompasses many different therapies and substances that are used to cleans the body's systems and organs. Proponents of detoxification believe the various approaches can cleanse the body, clear the skin, enhance the senses, help weight loss, improve fertility, improve flexibility, increase vitamin and mineral absorption, reduce blood fat levels, rejuvenate, rest organs, and slow the aging process. Detoxification has been suggested as a possible treatment for hives. However, there is currently no scientific evidence of its safety or effectiveness for this use.

In cases of illness the various forms of detoxification should be used under professional guidance. See specific monographs for precautions and warnings associated with modalities of detoxification.

Kudzu: Kudzu has been traditionally used in China to treat alcoholism, diabetes, gastroenteritis, and deafness. There are several species of pueraria throughout the world including Pueraria lobata and Pueraria Flos. Although kudzu has been suggested as a possible treatment for hives, there is currently no scientific evidence on the safety and efficacy of this use.

Use cautiously with anticoagulants/anti-platelet agents, blood pressure-lowering agents, hormones, antiarrhythmics, benzodiazepines, bisphosphonates, diabetes medications, drugs that are metabolized by the liver's cytochrome P450 enzymes, mecamylamine, neurologic agents, and methotrexate. No well-designed studies on the long-term effects of kudzu are available. Avoid if allergic or hypersensitive to Pueraria lobata or members of the Fabaceae/Leguminosae family. Avoid if pregnant or breastfeeding.

Moxibustion: Moxibustion is a therapeutic method in traditional Chinese medicine (TCM), classical acupuncture, and Japanese acupuncture. During the therapy, an herb, usually mugwort, is burned above the skin or on the acupuncture points to introduce heat into an acupuncture point to alleviate symptoms. It may be applied in the form of a cone, stick, or loose herb; or it may be placed on the head of an acupuncture needle, to manipulate the temperature gradient of the needle. There is limited evidence suggesting that moxibustion may help treat hives. Additional research is needed to evaluate the safety and efficacy of moxibustion for this use.

Use cautiously over large blood vessels and thin or weak skin. Avoid with aneurysms, "heat syndrome," heart disease, convulsions, cramps, diabetic neuropathy, extreme fatigue and/or anemia, fever, or inflammatory conditions. Avoid over allergic skin conditions, ulcerated sores, skin adhesions, inflamed areas, face, nipples, genitals, head, or contraindicated acupuncture points. Use cautiously after exercise or after a hot bath or shower. Use cautiously with elderly people with large vessels. Not advisable to bathe or shower for up to 24 hours after a moxibustion treatment. Avoid if pregnant or breastfeeding.

Peppermint oil: Peppermint is a flowering plant that grows throughout Europe and North America. Peppermint is most often grown for its fragrant oil. Peppermint oil has been used for many health conditions, including the common cold. Peppermint leaf has been used for stomach/intestinal disorders and for gallbladder disease. Historically, peppermint has been used to treat hives. Further research is needed to determine whether peppermint is safe and effective for this use.

Avoid if allergic or hypersensitive to peppermint or menthol. Peppermint is generally considered safe in non-allergic adults when taken in small doses. Use cautiously with G6PD deficiency or gallbladder disease. Menthol, which makes up part of peppermint oil, is generally considered safe in non-allergic adults. But, doses of menthol greater than one gram per kilogram of body weight may be deadly in humans. Avoid if pregnant or breastfeeding.

Probiotics: Probiotics are beneficial bacteria that are sometimes called friendly germs. They help maintain a healthy intestine and aid in digestion. They also help keep harmful bacteria and yeasts in the gut under control. Most probiotics come from food sources, especially cultured milk products. Probiotics can be taken as capsules, tablets, beverages, powders, yogurts, and other foods. Although probiotics have been suggested as a possible treatment for hives, there is insufficient scientific evidence on the safety and efficacy for this use.

Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.

General: The smallest amount of contrast agent should be used for each procedure. If multiple studies are needed, they should be performed at the same time. That way, patients only require a single dose of radiocontrast media, which reduces the chance of an adverse reaction. Patients should wait at least 48 hours between procedures that require radiocontrast media. Healthcare providers may recommend that the patient wait as long as five days between procedures. This allows the kidneys, which process radiocontrast media, to fully recover.

Traditionally, it has been suggested that adverse reactions, such as nausea and vomiting, are more common when the substance is injected quickly. However, recent research does not support this claim.

Patients should tell their healthcare providers if they are taking any drugs (prescription or over-the-counter), herbs, or supplements because they may interact with radiocontrast media.

Alternative imaging studies: If the patient has experienced a previous adverse reaction to radiocontrast media, an alternative imaging study that does not require the substance, such as a sonograph or magnetic resonance imaging (MRI) scan, should be considered.

Antioxidants: Several studies suggest that antioxidants may help reduce the risk of kidney damage in patients who receive radiocontrast media. Some studies suggest that 600 milligrams of an antioxidant called acetylcysteine twice daily, in combination with hydration, may help reduce the risk of kidney damage. According to the study authors, acetylcysteine plus hydrations is the treatment of choice to protect against radiographic contrast media-induced kidney damage.

Corticosteroids: Patients with a history of anaphylaxis-like reactions (moderate to severe) to radiocontrast media may receive drugs called corticosteroids to help prevent adverse reactions. For example, 50 milligrams of prednisolone (such as Deltasone® or Orasone®) has been taken by mouth 13 hours, seven hours, and one hour before radiocontrast media is injected into the patient.

Discontinuing certain medications: Patients who are taking drugs known to cause kidney damage, such as aminoglycoside antibiotics, should stop taking their medications under the supervision of their healthcare providers before they receive radiocontrast media. They can resume taking the drugs 48 hours after the imagine study is performed. This has been shown to reduce the risk of kidney damage.

Hydration: Research has shown that patients who are well hydrated are less likely to experience adverse reactions to radiocontrast media. Patients typically receive injections with 100 milliliters of saline per hour for four hours before the procedure and 24 hours after the procedure. It is also recommended that patients drink 500 milliliters of fluids before the procedure, followed by 2,500 milliliters over the course of 24 hours after the procedure.

Diuretics: Two diuretic drugs, mannitol (Resectisol®) and furosemide (Lasix®), have been studied as possible treatments to prevent kidney damage in patients who receive radiocontrast media. However, several studies suggest that these medications are not effective treatments.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.